1. Field of the Invention
This invention relates to regulator circuits, and is more particularly concerned with regulator circuits for integrated circuit appliance controls.
2. Description of the Prior Art
Home appliances which automatically operate through a sequence of operational states are generally known in the art and usually require a control circuit for selectively providing the desired cycles or series of machine modes of operation. For example, automatic clothes dryers generally have a number of different cycles or modes of operation, e.g. dry, cool-down, anti-wrinkle and off. Normally the control circuit will require electrical power from a regulated voltage source, and regulation of the voltage source is provided by conventional regulator circuits.
The use of integrated circuits in appliance control has given rise to a problem concerning voltage regulation in that, in some cases the integrated circuit chip may become unstable in response to low voltages and cause improper sequences of operation.
Carl R. Offutt in his U. S. Pat. No. 3,802,091, issued Apr. 9, 1974 and assigned to Whirlpool Corporation, the assignee of the present invention, discloses an integrated circuit dryer control which utilizes a regulator circuit which is interposed between a low voltage source and an integrated circuit for supplying a smooth DC voltage to the integrated circuit. This regulator includes a capacitor connected across the low voltage source and a transistor having its collector-emitter circuit connected in series between the low voltage source and the integrated circuit and its base-emitter circuit, including a Zener diode, connected across the integrated circuit. For this regulator circuit to operate effectively it is also necessary to provide a second, higher (approximately 110 volt) voltage source.